Simple population: \[\large N(t)\]
Age-structured: \[\large N_i(t) = \{N_1(t), N_2(t), ..., N_k(t)\}\]
- where \(i\) represents age structure, with \(k\) age stages
Spatial structure: \[\large N_i(t) = \{N_1(t), N_2(t), ..., N_k(t)\}\]
- where \(i\) is location, with \(k\) locations